Improvement in hydraulic jacks



8 Sheets-Shet 1. R. H. 8v G. T. LEWIS.

Hydraulic Jack.

No. 20|,|14. Patented March 12,1878.

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Hydraulic Jack.

No. 201,!14. I Patented March 12; 1878.

NVPEI'ERS. FHDTO-LITHQGRAPHER. WASHINGTON. U. C.

UNITED STATES PATENT OF Io ROBERT LEWIS-AND GEORGE 'r. LEwIs, orPITTSBURG, PENNSYLVANIA.

IMPROVEMENT IN HYDRAULIC JACKS.

Specification forming part of Letters Patent No. 201-,1 14., dated March12, 1878 application filed January 9, 1878.

To all whom it may concern:

Be it known that we, ROBERT E. LEwIs and GEORGE T. LEWIS,-Of Pittsburg,in the county of Allegheny and State of Pennsylvania, have invented anewand useful-Improvement in Hydraulic Jacks; and we do hereby declarethefollowing to be a full, clear, and exact description thereof,reference being had to the accompanying drawing, forming part of thisspecification, in which- 1 L Figure 1 is an elevation of devicesembodying our invention. Fig. 2 is 'a vertical central section. Fig. 3is a perspective view of the base, partly. in section. Fig. 4 is anunder side view of the base, the bottom cap being removed; and Fig. 5 isa modification in the arrangement of the parts within the base.

Like letters refer to like parts wherever they occur.

Our inventiourelates to the construction of hydraulic jacks; andconsists, first, in arranging the reservoir-pump, plunger, and valvesentirely within the base, and combining them therewith, so "as to obtaina light, compact,

and balanced jack, wherein any leak from the pump escapes into thereservoir, avoiding loss and waste of liquid; secondly, in connectingthe pressure-cylinder and reservoir by a channel, whereby anyliquidcscaping past the rain.

or its packing will be returned or find its way back to the reservoir,thereby avoiding leakage and waste; thirdly, in combining with thereservoir an air-expansion or relief chamber, to relieve the reservoirof any compressed air which might otherwise accumulate therein andretard the fall of the ram; fourthly, in providing the pressure-cylinderwith an independent discharge-valve, which is seated by the pressure ofthe liquid-in the cylinder, and is adapted to be tripped by a hollowscrew trip or tap devices to permit the fall of the ram; and, finally,in details of construction, hereinafter more specifically set forth.

We will now proceed to describe our invention, so that others skilled inthe art to which it appertains may apply the same.

In the drawing, A represents the base, hollowed out to form thereservoir a, which connects, by ports a M, with the pump-chamber B. Brepresents the pump-chamber, bored or can. be removed to get at port a?and the valvestem.

cylinder,) which-is seated in the-bottom of the pressure-cylinder, andcloses the port'c, leading from the pump-chamber to'thepressurecylinder.

D is the pump piston or plunger, which extends across the reservoir a,projecting into'a guide, (1, which latter is, preferably, a screwcap,which can be removed for insertion or withdrawal of the plunger D. Theplunger is usuallyslotted, as shown at d, and is operated by a crank, dlocated within the reservoir, and operated by a shaft, at, whichprojects through the walls of the reservoir, said shaft being fittedwith a stuffing box, d whereby all leakage from the reservoir isprevented. y r

V The plunger D is made to work tight in pump-chamber B- by means of apacking-ring, e, fitted in a suitable recess of the pump-chamber, andbacked by an annular screw'follower or nut, e, flush with the walls ofthe reservoir, which is found to be efiective and durable, and to permita longer stroke of the plunger than could otherwise be obtained in theneoess'arily limited space wherein the plunger acts.

G indicates the pressure-cylinder, properly secured in the base A at apoint over the pumpchamber B, and inclosing the ram H, which is packedat its lower end by the leather cup h and nut or follower h. Surroundingand inclosing the pressure-cylinder is a second cylinder, I, closedabove to form an annular chamber, i, which communicates below with thereservoir a by means of one or more ports or passages, r. This chamberthus formed serves as an air-space, to receive the contained airexpansion or relief of the reservoir a when the liquid from thepressure-cylinder is permitted to return to the reservoir, as inlowering the ram,

0 represents the discharge-valve of the pumpchamber, (or receiving-valve of the pressurethereby avoiding the resistance sometimes offeredto the descent of the ram by the corn pression of air in the reservoir.

A port, (or ports,) 19, formed in the upper part of thepressure-cylinder G, establishes communication between the upper part ofthe pressure-cylinder and the annular chamber 2', permitting the returnto the reservoir of any liquid which escapes past the packing of theram.

- It will thus be seen that the annular chamber '5 serves two functions;but where the airchamber is not desired it may be omitted, and a simplechannel or tube may connect the top of the pressure-cylinder with thereservoir, and in other cases where the return-channel is not desiredthe port 19 may be omitted or the air-chamber difl'erently located. anindicates the discharge-valve of the pressure-cylinder, located in thebottom thereof, and adjusted so as to be held upon its seat (or closed)by the pressure of the liquid in the pressurecylinder, and adapted to betripped from without when the ram is to be lowered. This valve isprovided with a stem extending into the port leading from the bottom ofthe pressurecy'lindcr directly to the reservoir, and is tripped by meansof a hollow threaded tap, n, Fig. 3, which, when screwed in, forces thevalve m 011' its seat and permits the liquid from'the press urecylinderto pass through valve-port o and hollow tap a to reservoir a. -Tindicates a screw-plug, which may be removed for filling the reservoir.

The base A may be closed by a threaded cap, A, and interposed gaskets a,so as to be removed for examination and repair of the parts.

The modification shown in Fig. 5 is merely a matter of form, to permitthe pressure-cylinder to be placed on the center of the base instead ofat the side, as in Fig. 2 but in all cases where the jack is to be usedto lift directly from the ground, it is preferred to construct the baseso that the pressure-cylinder will sit at the side, and the Z-hook maybe used.

The operation of the devices is similar to that of other hydraulicjacks, and need not be specifically stated.

The advantages are compactness, lightness, efl'ectiveness, anddurability.

The manner of packing the plunger insures a perfect joint. Theconstruction of the independent pressure-eylinder relief-valve obviatesthe liability of its either wearing loose and leaking, or sticking uponits seat and arresting the fall of the ram. The return-channel from thetop of the pressure-cylinder obviates waste of liquid, and theair-chamber prevents the compression of air in the reservoir, so as toretard the fall of the ram.

Having thus described our invention, what we claim, and desire to secureby Letters Patcut, is-- 1. In a hydraulic jack having a rampressure-cylinder and reservoir-base, the combination of the horizontalpump-plunger D with the pump-chamber B, having valves 1) and a, V

and with guide-cap d, the whole arranged and constructed substantiallyas described.

2. In ahydraulic jack, the combination, with the pump-plunger, of thepacking e and annular screw-follower 6, let into the walls ofthepump-chamber, and flush with the reser voir-wall, substantially asand for the purpose specified.

3. In a hydraulic jack, the reservoir provided with an expansion orrelief air-chamber, substantially as and for the purpose specified.

4. The combination, with the pressure-cylinder and reservoir, of areturn-channel connecting the upper part of the pressure-cylinder andthe reservoir,.substantially as and for the purpose specified.

5. In combination with, the pressure-cylinder. and reservoir of ahydraulic jack, a discharge-valve constructed and adapted to be held onits seat by the pressure within the cylinder, and a hollow screw trip ortap, substantially as and for the purpose specified.

In testimony whereof we, the said ROBERT H. LEWIS and GEORGE '1. LEwIs,have hereunto set our hands.

ROBERT H. LEWIS. GEORGE T. LEWIS.

Witnesses:

J AMEs I. KAY, F. W. BITTER, Jr.

